test: add global test setup with screen limits and reach 1337 tests

- Add test/setup.ts with max 10 concurrent screen sessions limiter
- Add orphaned Claude/screen process cleanup before/after tests
- Add semaphore-based screen slot acquisition for concurrency control
- Update vitest.config.ts with setupFiles and fileParallelism: false
- Add 16 new test files for comprehensive coverage
- Update README badge to show 1337 total tests
- Update CLAUDE.md with test setup documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

vitest.config.ts

@@ -5,6 +5,10 @@ export default defineConfig({
     globals: true,
     environment: 'node',
     include: ['test/**/*.test.ts'],
+    setupFiles: ['./test/setup.ts'],
+    // Run test files sequentially to respect screen session limits
+    // Individual tests within files still run in parallel where safe
+    fileParallelism: false,
     coverage: {
       provider: 'v8',
       reporter: ['text', 'json', 'html'],
@@ -12,5 +16,7 @@ export default defineConfig({
       exclude: ['src/index.ts', 'src/cli.ts'],
     },
     testTimeout: 30000, // 30 seconds for integration tests
+    // Ensure cleanup runs even on test failures
+    teardownTimeout: 60000,
   },
 });